On November 8, millions of voters will turn out to decide whether Hillary Clinton or Donald Trump will be the next president of the United States. And millions of eligible voters will just stay home.

Voter turnout in the United States is incredibly low compared to other modern democracies. In the 2012 presidential election, 53.6 percent of the voting-age population turned out to vote. This puts the United States well behind countries such as Turkey (84.3 percent turnout in 2015) and Belgium (87.2 percent in 2014), where voting is compulsory. But the U.S. also lags behind other countries with voluntary voting, such as Sweden (82.6 percent turnout in 2014), France (71.6 percent in 2012) and many others. In fact, the U.S. ranks 31st out of 35 developed countries in voter turnout, according to a recent Pew Research Center study.

It’s a little surprising that Americans are such unenthusiastic voters because they are fairly interested in politics, notes Mert Moral, a political scientist at the State University of New York at Binghamton. “If you look at survey data you find more Americans are equally if not more engaged than their counterparts [in other countries],” he says. “They have bumper stickers, they talk about politics [and] they are interested in political topics at the local level.”

Why don’t people vote? Below are four well-studied reasons why people may not head to the polls on November 8, followed by four tactics to get more people to go to the ballot box.

Voter registration takes work.

In many countries, people are automatically registered to vote. Not so in the United States. “The U.S. system puts the burden on the voter,” says Barry Burden, a political scientist at the University of Wisconsin–Madison. A 2012 Pew Research Center study reported that 51 million eligible citizens aren’t registered to vote. Easier registration could bring that number down and, hopefully, boost the number of people who vote. In a 2013 study in the American Journal of Political Science, Burden and his colleagues showed that over the 2004 and 2008 presidential elections, allowing people to register to vote at the polls on Election Day increased voter turnout.

Lack of a college education — and all that comes with it.

The single biggest predictor of whether or not people will vote, Burden says, is education level, which has direct and indirect effects on voting. “People are more likely to vote if they have information about the candidates and the process of voting, higher levels of income and education, find themselves living and working in networks of other people who vote,” he says. “Other people who are disadvantaged in those ways are much less likely.”

Two parties may not be enough.

In a two-party system, people might not be able to find someone who represents their views. And if they don’t, Moral says, they might just stay home. “A third-party candidate can’t win an election here,” he says. “This makes people vote for major party candidates or they don’t turn out at all.”

People get burned out, and sometimes just don’t care.

There are some people who just don’t care about politics. Some people who don’t vote are people “in social groups [that don’t] really regard politics as an important issue,” explains Eyal Winter, an economist at the University of Leicester in England and the Hebrew University of Jerusalem in Israel. And strictly rationally, he notes, “it makes no sense to vote.” It’s very rare for a single vote to change the outcome of an election, and most cases are limited to small, local races. Most of the time, your personal vote just isn’t going to make a difference. Why bother?

And too many elections might make voters face burnout. “One of the things that makes the U.S. strange is that there [are] a lot of elections,” says Burden. “We ask voters to make a lot of decisions.” Getting out to the polls can be a hassle, and learning about every single issue takes time. “We have a complicated system and I think that produces fatigue.”

What works in getting people to the polls

No matter what the party, politicians and many citizens want to see their side turn out as much as possible. Facebook users plead with their friends. Politicians hire phone banks to call thousands of people in battleground states. Celebrities beg over YouTube. But four main methods seem to stand out.

Educate early and often, and make voting mandatory.

The messages people receive early in life have a strong impact on whether people vote, says Donald Green, a political scientist at Columbia University in New York City. It helps if parents and teachers let kids know “voting is important — it’s what makes you a functioning adult.” This message may come through in civics and government classes.

More education increases the likelihood of voter turnout. But one does not simply send everyone to college to boost voting. Another way to increase turnout is to make it required. Using data from 28 advanced countries, Aina Gallego, a political scientist at the Institute of Public Goods and Policies at the University of Barcelona in Spain, showed in a 2010 study that compulsory voting reduced inequalities in education and voter turnout — simply because everyone had to go do it.

Unfortunately, you can lead voters to the polls, but you can’t make them have an opinion on the candidates. Moral examined 18 European party systems and found that compulsory voting goes hand in hand with increased numbers of spoiled and invalid ballots — slashing through them, turning them in blank, or writing in a candidate like “Mickey Mouse.” Not voting may result in a fine, but it’s also costly to get informed on the issues, he says. The net result is that politically uninformed people may “go out to vote, they don’t know who to vote for and they spoil their ballot.” Moral published his results August 9 in Political Research Quarterly.

Peer pressure people to the polls.

A healthy dose of name-and-shame can have a big effect on Election Day. In a 2008 study in American Political Science Review, Green and his colleagues applied a little social pressure to voters. They sent 180,000 people in Michigan (where voting records are publicly available) a series of mailings before the August 2006 Republican primary for the state elections.

Simply asking people to vote resulted in a 1.8 percentage point increase in turnout. Asking people to vote and notifying them that they were being studied — and that their votes were a matter of public record — increased turnout by 2.5 percentage points. But when the mailings also displayed the voter’s previous voting behavior to the voter and other people in their household, there was a 4.9 percentage point increase in voter turnout compared with people who didn’t get a mailing. If the voters were then also shown their neighbors’ voting records, there was an 8.1 percentage point bump in voter turnout.

But while shame may get out the vote, Green cautions that it probably also burns bridges. “I think it produces backlash,” he says, the most heavy-handed naming and shaming especially. In their study, Green and his colleagues noticed that people who received the most shame-heavy mailings also tended to call the number on the mailings — and demand to be left alone.

More positive peer pressure might prove effective without the dose of shame, Green notes. Get people to pledge that they’ll show up, and remind them that voting is a matter of public record. “Maybe the most effective is a close friend or coworker who says ‘let’s walk to the polls together,’” he says.

A little healthy competition never hurt.

They don’t call elections “races” for nothing. In a 2006 study looking at U.S. gubernatorial races from 1990 to 2005, Winter and his colleague Esteban Klor at the Hebrew University of Jerusalem looked at differences between who was leading in the polls prior to elections and the voting results for those races. They found that when polling numbers are close, voter turnout increases, especially for the side with the slight majority in the poll. “It’s nicer to support your team when you’re expected to win,” Winter explains. Close races, while nail-biting for candidates and voters alike, might make people turn out in higher numbers.

But of course, if you want to have healthy competition, it’s best to have likeable candidates. When it comes to the upcoming presidential race, Burden says he would not be surprised if turnout is even lower than usual. “That’s where things are pushing,” he says. “We know surveys have shown these two nominees have lower favorability ratings than any two other nominees in the history of polling.” Those low favorability ratings may keep people away on Election Day.

The personal touch is best.

Hundreds of nonpartisan, bipartisan and partisan studies have been done on how to win campaigns and influence people, looking at everything from the cost per vote of robo-calls to how to craft the perfect email subject line. But the most effective message is face-to-face and one-on-one, says Green, who, along with colleague Alan Gerber of Yale University, wrote the book, Get out the Vote: How to increase voter turnout.

For politicians, this means getting out and canvassing the streets. But maybe someone just wants to get their sister, friend or spouse to vote. In that case, he says “the most effective message would be to express your own interest in the election, your own desire to vote and your own desire to see them vote.” Getting them to vote the way you want them to, however? That’s a different matter.